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L, A. WBTTE TUNNEL MLN INVENTOR 5 Sheets-Sheet 2 Attorneys, I Mwm LJLM/Q fi Mgg Filed June 24. 1918 www5 5 Sheeis-Sheet 5 INVENTOR ByAttorney,

F l l L. A. WITTE TUNNEL KILN Filed Juney 24.

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L.. A, WITTE TUNNEL KILN Filed Ju'ne 24, 1918 5 SheetsSheet 4 INVENTORZilli/1C,

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` www5 I.` A. WITTE TUNNEL KILN 5 Sheets-Sheet-5 Filed June 24 1918INVENTOR By orneys, @Vga/ml Oom/Q d w Patented @et 23, i923.

blt S naar LOUIS A. WITTE; ELIZABETH WITTE DMINISTRATRIX 0F SAID LOUISWITTE,

DECEASED, F METUCHEN BOROUGH, NEW JERSEY. i

TUNNEL KILN.

To all 'whom t may concer/1L.'

Be it known that I, LOUIS A. WITTE, a citizen of the United States ofAmerica, residing in borough of Metuchen, in the county of Middlesex andState of New Jersey, have invented certain new and useful Im rovementsin Tunnel Kilns, of which -the fol owing is a specification.

This invention relates to kilns or ovens of the tunnel type, the waresto be subjected to heat treatment being carried through a longitudinaltunnel chamber on suitable cars. Such kilns are useful for variousbaking, roasting, annealing or tiring opera.- tions. They are used forexample for the annealing of metal articles and for the liring ofporcelains.

Tunnel kilns are of two general types: (l) those in which the wares tobe fired (or their enclosing receptacles 'or saggers) are exposed todirect contact with thev flames or with the hot fire gases or productsof combustion, such kilns being commonly used for the tirin of earthenware or porcelain, and for t e firing of bricks or the like, and forother similar pur oses; and (2) those of the type of mulile urnaces inwhich the tunnel chamber is formed with a lining or shell which isheated externally Wyhich the heat is transmitted to the wares or theirreceptacles carried on the cars so that the wares or receptacles are notexposed to direct contact with fire gases.

The present invention relates particularly to the latter or muiiie typeof tunnel kilns, although in its generic features it is- 'appli'cable inpart to the former or open tunnel t pe.

In eitlier type of tunnel kiln it is Ivcustomary to divide the lengthofthe tunnel into three zones, viz: 1) a heating-up zone in traversingwhich the car-loads of wares to be treated are exposed to the heat ofthe 'waste re gases, and are thereby gradually heated up as theyprogress toward the zone .of highest temperature; (2) the tiring zone,or zone of highest temperature, where the heat treatment is accomplishedand which approximately coincides with the zone in which the combustionof fuel takes place; and (3) the cooling-0133 zone, in which the waresas they progress away from the firing zone are gradually cooled, theirheat being bix the combustion of gases, and through" Application iled.Tune 24, 1918. Serial No. 241,472.

commonly economized by being used to preheat the entering air which isto support the combustion.

The principal object of the present invention is to provide for the moreeffective control or grading of the tempera-ture lon itudinally of thefurnacel throughout the ring zone. Heretofore in tunnel kilns the heathas been generated in' lcombustion chambers extending longitudinally ofthe tunnel, and in chambers thus located it is impossiblel to accomplishany close regulation or grading of the temperature, because the burninggases or flames travel in a longitudinal direction. Attempts to controlthe combustion by introducing thereto fuel at successive longitudinalpoints in such combustion chambers have been only partially successful.Accordin to the present invention heat is generatedg in a` seriesof'distinct combustion chambers arranged transversely of the tunnel, andin each of which the conibustion is regulated independently of theothers. Any desired number of such combustion chambers may be providedaccording to the desired length of the firing zone. By this means anydesired heating effect may be obtained, the greatest heat being impartedeither at the beginning, middle or end of thering zone, or aleveltemperature being maintained throughout such zone, as mayberequired for any particular service; or the tiring zone may belengthened or shortened by throwing one or more of the combustionchambers into or out of service.

Another important object of the present invention is to provide meansfor more effectively utilizing the heat of the waste fire gases forpreliminary heating up of the wares to be treated; and for moreeffectively accomplishin the cooling off of the treated wares andutilizing the heat radiated therefrom for the heating of air for suporting combustion, or for other uses. To these ends flues are providedbetween the mume or tunnel lining and the masonry structure of the kiln,in which the air or gas is caused to ilow repeatedly back and forthacross the roof of the tunnel andA *ies against the sides thereof.- 'i

The invention further provides anim proved tunnel kiln structure,possessing many advantages in the building lof the kiln, inthe repair orreplacement of burntout parts, and in the adjustment or adaptation ofthe kiln for varying requirements.

The preferred form of muiiie kiln embodying this invention isillustrated in the accompanying drawings, wherein,-

Figs. 1 and 2 are schematic plans in horizontal section, the formel`illustrating the circulation of the entering air, of the combustiongases and thewaste fire gases; and

lthe latter illustrating at the right-hand end the air circulation forthe final cooling-oil' of the treated wares, and in its remainingportion the circulation of gaseous fuel.

Fig. 3 is a vertical longitudinal section of the'furnace, and Fig. 3 isa continuation thereof. These views are in vertical midsection exceptfor the portions indicated by the arrows 3", 3, 3d and 3 which arerespectively in vertical longitudinal planes denoted by thecorrespondingly lettered dotted lines in the later figures.

Figs. 4 to 10 inclusive are one-half sections grouped in pairs (Fig. 10with Fig. 11) and being respectively upon the planes of thecorrespondingly numbered lines in Figs. 3 and 3a.

Fig. 11 is a half elevation at the emerging end where the cars pass out.

Fig. 12 is a horizontal section, the upper half being on the plane ofthe lines 12a in Figs. 4-10 and 15; the lower half is in the plane ofthe line 12b in Figs. 7-9.

Figs. 13 and 15 are transverse sections in the same planes respectivelyas Figs. 8 and 6, showing the furnace partly built.

Fig. 14 is a perspective of one of the par-v tition tiles in Fig. 13,and

Fig. 16 is a similar perspective of one of the tiles in Fig. 15.

Figs. 17 and 18 are respectively an enlargement of a flue 54 shown inFig. 10, and a cross-section thereof.

The entire structure is built up of masonry upon suitable foundations soas to form a tunnel chamber A through which travel cars B (Figs. 10 and11) running on rails 20 supported on. girders 21 which bridge across apit C.

vThe main masonry structure of the tunnel designated as a whole by theletter D comprises side walls, and a roof, the latter formed preferablyas an arch E. This masonry structure or arch (whatever may be its form)is considerably larger than the tunnel chamber A, so as to affordbetween them a flue space, as is clearly shown in Figs. 8 and 9; or acorresponding combus- .tion space as is shown in Fig. 6. This flue orcombustion space is separated from the tunnel chamber by a succession ofrelatively thin refractory tiles forring the inutile partition or tunnellining F. The tunnel chamber A is continuous from the`entering end (Fig.3), which is provided with a door G, to the emerging end (Fig. 3a) whichis provided with a door G'. The cars carrying the goods or wares to betreated are introduced through the door G and are propelled forwardthrough the tunnel, either continuously orintermittently by means of anyknown or suitable mechanism, such for example as a chain propellerapparatus such as is schematically indicated'at H in Figs. 3 and 4, anendless chain 22 being carried on pulle s and driven from any suitablesource o power and carrying any suitable means for engaging the cars topush them ahead; such apparatus being well under-v stood and formingno-part of this invention, requires no further description.

The flue space between the arch or other structure E and the mufliepartition or tunnel lining F is divided at frequent intervals to providetransverse flues and combustion llo the kiln the transverse partitions24 form\ 95 a succession or series of combustion cham` bers J J flankingthe tunnel chamber, one such combustion chamber being shown in Fig. 6,and others in the section 3b of Fig. 3. The number of these chambers mayvary 'according to requirements, the kiln illustrate-d having, forexample, ten pairs of such combustion chambers, of which all or any partmaybe used.

' The fueli-for heating the kiln may be keither gas oloil, or solidfuel, as coal or coal dust. Tf oil is used, it will be injected into thecombustion chambers .by means of an atomzer in the well-known manner, byusing either compressed" air ory steam. If gas is used, it may be eitherproducer gas, natural gas or gas from other sources.. For using coal'dust any of the known means ma be used for flowing it in. For burningsolld coal, the usual grate bars will be provided.

The furnace illustrated is designed for using gas, which is admittedthrough a gas main K, Fig. 2. This main extends across the pit C, asshown in Fig. 3, so as to serve both sides of the kiln. From it leadflues 30 which lead to distribution flues 31 on opposite sides,theseflues extending longitudinally through the flanks of the kiln, and"beneath the level of the combustion chambers; From these tlues gasinlets 32 lead upward into the bottoms of the combustion chambers (seeFig. 6), the How of gas through each of such inlets being controlled bymeans-of a damper 33 consisting of a. brick or tile resting on thehearth of the combustion chamber, and which may be moved by means of apoker inserted through a hole 34 to close more or less of the inletopening 32.

The air to support combustion enters at the emerging end of the furnacethrough inlet openings on opposite sides (Fig. 1), one such inlet beingshown in Fig. 10; and Hows thence longitudinally through air heatingfiues L L, which are shown in Fig. 1, alongside the tunnel chamber inthe coolingo zone, where heat is being given ofl by the wares as theycool. The air flows in a direction contrary to the movement of the cars,and consequently as it becomes heated, it enters continually a hotterportion of the cooling-0H zone. The lues L L unite in a flue 36, whencethe air flows back and forth through a succession of transverse flues LL (Fig. 1) which pass back and forth across the top of the tunnelchamber and extend down the sides thereof, as shown in Figs. 8 and 9.These ues are separated by the partition tiles 23 already referred to,which on each alternate side extend down to the floor of the masonry (asshown in Fig. 9), the intervening tiles terminating at 25, so as toleave an opening 26 beneath (as shown in Fig. 8) through which the airflows to the next transverse flue ahead. The air is thus givenl azigzagcourse surround* ing the hottest portion of the cooling-olf zoneof the kiln. The terminal cross flue 37 (Figs. 1 and 7 discharges toboth sides of the kiln through an outwardly directed branch 38, andthence upwardly, as shown in Fig. 7, under control ofa damper 38 into atrunk flue M. rlhe flues M on opposite sides are located with respectvto the combustion chambers J in the manner shown in Fig. 6, and fromthem lead downwardly branches 39 k:from which the air flowsthroughopenings 40 into the respective combustion chambers. Each opening40 is formed in a ledge or sole-plate 41, over which is placed a damper42 consisting of' a brick or tile, which may be adjusted by a pokerinserted through a hole 43 to more or less close the opening 40, andthereby regulate the admission of air. Beneath the sole-plate 41 is apeep-hole 44 through which the combustion may be observed, and throughwhich a pyrometer may be inserted into the combustion chamber d' ifdesired.

lin each combustion chamber J the combustion is regulated by suitablyadjusting the dempers 33 and 42` accord-ing to the quality of gas used,the intensity of the heat to he generated in the combustion chamber, andany other controlling conditions. Normally the ccmhustion chamber J willbe more er filled 'with i'ilames or burning acc *ata g te the amount offuel admitted, desirable adjustment of the air damper being such as to'perfect the combustion. The hot lire gases rise through the uprightportion of the combustion chamber, imparting heat to the side tiles ofthe tunnel lining F,'and thence follow the arch over the top of thetunnel chamber, whereby the top lining tiles thereof are heated. Fromthe pair of combustion chambers on opposite sides ofthe tunnel the firegases flow together in transverse eduction chamber 45, and pass outthrough openings 27 in the upper tiles 24, ilo-wing thence in thedirection indicated by the small arrows in Fig. 1 toward t-he stack oroutlet and into the next following transverse chamber 45, uniting thenext pair of combustion chambers in advance. The openings 27 may vary innumber and size, five openings being shown partly in the half section(Fig. 6) and partly in Fig. 15, which showsvthe entire series of tiles.

From this construction there results a cumulative flow of fire gases orhot products of combustion from the connecting chambers 45 of thesuccessive pairs of combustion chambers. As compared with taking thefire gases immediately upward from the pairs of combustion chambers intoan overhead trunk flue leading tothe stack, this construct-ion has theadvantage of keeping the hot gases down close against the ceiling of thetunnel lining F so that their heat is most efficiently imparted to suchlining, whereby the top of the tunnel lining, which is the mostdifiicult portion to heat, is thereby heated in the most efficientmanner. In the successive chambers 45 there is, following the flow ofthegases, an increasing or cumulative volume of gases flowing, and-thisvarying volume may be provided for by proportionately varying the sizesof the openings 27, if such be desired, or be in any given case foundnecessary. 'lhe tiles 24 may be formed with openings of graded sizes, orthe openings may be of the maximum size and be more or less restrictedby blocking them by inserting lire y sc that alternate openings 47 areprovided! beneath the partitions, whereby the waste gases are caused toHow alternately back and forth over the top of the tunnel chamber anddown the sides thereof, whereby their waste heat is effectively impartedto heat theA tunnel lining F, and 'thereby transmit heat toheat up thewares which are progressing through the heating-up zone toward thefiring zone. The final transverse flue 4S, shown in Figs. 1 and 4. leadsto an outflow opening 49, controlled by a damper and leading to theintake 51 of a suction fan l. Preferably the partitions limiting theflues 46 and 48 are provided with openings 52 and 53 respectively(Fig. 1) for short-circuiting a portion of the flow of gases.

`The air inlet trunk flues L absorb only a portion of the heat given 0Hby the treated wares in the cooling ofi' zone. Ordinarily, these waresgive oft more heat than can be utilized for preheating the air tosupport combustion. It is desirable to utilize this surplus heat and toafford the most efficient cooling of the treated wares; and for thesepurposes this invention provides additional air cooling means comprisingtransverse flues, crossing and re-crossing the top of the tunnelchamber, and through which the air is caused to fiow. The preferredconstruction is that` shown in Figs. 2. 3a and 10. Large tubes 54 whichmay be of cast iron are arranged to cross the top of the tunnel chamberA, these being arranged in successive series, as shown in Fig. 2 Air isforced in by means of a fan P (Figs. 10 and 11) through an inlet 55controlled by a damper 56 into a flue 57 which distributes the air tothe transverse pipes 54 of the first crossover series (shown as threepipes in Fig. 2), whence the air enters a flue 58 on the opposite sidewhich distributes it to the next cross-over series of pipes 54 (shown asconsisting of four pipes); from .these the air enters a flue 59, whenceit is distributed to the third cross-over series of iron pipes(comprising five pipes as shown), and from these it enters flue 60,whence it flows through the last` series of cross-over pipes (shown alsoas comprising five pipes), and is collected in a flue 61, whence itpasses to an uptake 62.(Fig. 3a), from which a conduit may lead theheated air to any place where its heat may be utilized, as for examplefor feeding a gas producer. As the heat from the car-loads of hot Warestends to rise, it is very eiciently conducted to vthe extended surfaceof the pipes 54, and from these pipes the heat is imparted to the forcedcurrents of air flowing through them. The length ofthe cooling zone withcrossover pipes 54 may be varied as required, and consequently thenumber of these pipes, and the number of groups of pipes may be greatlyvaried.

To facilitate the conduction of heat to the air, it is desirable toprovide the pipes 54 with internal projections which are bestconstructed as shownin Figs. 17 and 18. These gures show lugs or slenderprojections 55. such as iron nails, which are cast integrally with orfastened strongly to the pipe 54, and projectoa suitable distance intothe pipe, so that they enter the stream of air and conduct the heateffectively thereto.

Certain details of construction remain to be described.

Nearly the entire length of the tunnel chamber A is enclosed by thelining F, which is formed of tiles or slabs of suitable refractorymaterial. These tiles are located by the successive transversepartitions 23- and 24, which partitions are built into the masonrystructure at their outer portions and project thence inwardly,terminating coincidently with the outline of the tunnel chamber. Thesides of the tunnel chamber are formed by the lining tiles 63 (Figs. 4and 5) which rest. on the member 64 which is built into the hearthportion of the kiln in the usual manner. This member 64 has in its upperface a groove which makes a free engagement with a flange on the bottomof the tiles. In building the furnace the masonry structure is erected,and the lining tiles are last applied. The side tiles 63 are first putin place from the inside. These t-iles are of a width equal to thedistance between centers of the partitions `23, 23 and 24, 24. and arepushed outwardly into place against these partitions, being located asshown in Fig. 12. The top tiles are then put in place and serve toprevent the tiles 63 from falling inward, The top tiles have each awidth equal to the flues or chambers formed between the partitions 23,23 and 24` 24. These. partitions are formed with a bottom fiange 28,shown in Figs. 1.346 on each side on which fianges the top tiles rest,as shown in Figs. 3 and 3a. The middle top tile 65 is first put inplace, and then the lateral top tiles 66-66 (Figs-8 and 9) are applied,resting partly on the tile 65 and partly on the tops of the side tlles63 and interlocking with the latter, so as to hold their upper ends inplace.

The partitions 23 and 24 are best made of segmental tiles of fire-brick.as shown in Figs. 13 and 15, in which figures the tunnel lining F isomitted. These radial tiles, of 'which examples are shown in Figs.' 14and 16, are interlocked with the masonry arch at their outer portions,being for lthis purpose preferably built with upper or outer flanges 29.The tiles for the partition 24 differ from the tiles 23 only in thatthose over the top of the tunnel chamber are formed with the openings27, as shown in Figs. 15 and 16. The described construction of thepartitions 23 and 24 provides a very convenient means of forming therespective combustion chambers and transverse zig-zag flues, and at thesaine time gives very secure support to the lining tiles of the tunnelchamber. 'lihese tiles are made as thin as possible consistent withstrength, in order to transmit heat readily,

and are thereforel the weakest part of theV entire structure; by themeans described they are so electively supported that breakage isextremely unlikely.

It is desirable to be able to get access to close fitting lid 69. Byremoving the lid 69 when the kiln is in operation the temperature in thechamber or flue beneath may be taken by introducing a pyrometer. Thetile directly beneath this man-hole has a central stopper 70, which maybe removed to insert a pyrometer into the tunnel chamber proper. When itbecomes desirable to make repairs or readjustments, it is only necessaryto` shut oif the gas for a suitable time, and then remove the lid 69 andcover 68 from any man-hole, whereupon a workman may reach down withsuitable tools into the flue or chamber beneath, and make any necessaryrepairs to the partitions on either side, or in the same way access maybe had to the openings 27 for enlargingl or contracting them as occasionmay req'uire. Man-holes may be provided for all the chambers or iuesinstead of lthe alternate ones if preferred.

For more conveniently taking the temperature in the successive lues orcombustion chambers, peep-holes 71 indicated in dotted lines in Figs. 3and 3, or in section in Fig. 4, may be provided. These with thepeep-holes 44 (Fig. 6) for giving access to the combustion chambers willenable all neceary temperature measurements to be taken.

\ The inner facings of all combustion chambers and lues should, ofcourse, be formed of fire-brick or tile. The outer structural portionsof the kiln may be built of ordi? nary brick. In between these it isreferable to provide a layer of insulating rick orother heat insulatingmedium, as shown at 72 in the respective figures. The masonry structurewill be stiened in the well understood manner by the use of tie-rods andholsters. rllhe cars used should have refractory oors, and to preventundue heat reaching their running gear or entering the plit C, the usualsand lutlng 1s provided, t e sand being introduced through hoppers, oneof which is shown at 73 in Fig. 3.

For getting access to the several dues, clean-out openings arelleft atsuitable posi= tions in the ermanent masonry, these openings being lledwith brick laid loose and grouted with any sultable plastic materlal,

Such as clay, which can be broken out when it is desired to open theclean-outs. Such clean-out openings filled with loose bricks areindicated at 74 in Fig. 4, at 75 in Fig. 5, and at 76 in Figl forgetting access to the air flue M, and at 77, 78 and 79 in F i0'. 2 forgetting access to the gas l'lues 31.

n operating the described furnace, it is generally preferable, tovmaintain a slight pressure in the air and gas admission tlues,combustion chambers and waste gas tlues, as thereby a higher temperatureis-maintained which greatly increases the capacity'of the kiln, and theheating is more uniform. To

attain this result, it is only necessary to force in the fuel-gas, andthe air for maintaining combustion, by means of blowers or other forcingapparatus.

In treating articles coated with oil or containing volatilehydrocarbons, it is desirable to draw oil' the hydrocarbon gas generatedby the heat, either continuously or intermittently. This as if richenough may be utilized for com ustion purposes. Where the gas isproduced continuously in sufiicient quantities, it is preferable to drawit of? continuously by means of a. special suction Afan which should belocated at the admission end of the kiln. This gas may for example bedrawn oil1 through an outlet conduit 8O (Fig. 3). Where the gasesroduced are not so rich, or are produced in very small quantities, it issufiicient to draw them od at intervals. `When the gases are not ofsuiiicient Value to justify separate treatment, it is neverthelessimportant to remove them in order to avoid their generaltin anyobjectionable pressure in the tunne which might occasion diliiculty inoperating the end doors, or which might lead to possible'explosions. Tothis end an opening 81 is provlded through the top tile communicatingwith the terminal flue 48 of the series N or elsewhere adjacent to theuptake 49, this opening being covered by a lid or damper 82 which may beoperated through any Vsuitable opening whereby it may be displacedeither occasionally for intermittent drawing 0H' of the gases, or veryslightly for continuous drawing od' thereof, by the exhaust fan. Instead'of an exhaust fan drawing from the Hue 51, a stack or chimney may beused.

lt must not be inferred from the detailed illustration and descriptiongiven that the invention is necessarily' limi-ted toY the pireciseconstruction shown, or to any` resembling this construction, as it 1sWithin the invention to vary the constructive features within widelimits as determinedby the skill and judgment of the designing engineer,in order to adapt the kiln toan specific purpose for which it may bedesire The essential features ofthe lnventlon are those rstherei'nbetore stated, and those ist particularly set forth in thefollowing claims:

I claim as my inventionz l. A tunnel kiln comprising a continuous liningforming a tunnel chamber and an enclosing masonry structure forming anintervening space divided by transverse partitions, said structurehaving a central zone with combustion chambers, a heating up Zone withflues for the circulation of combustion gases through such space aroundthe chamber, and a cooling zone with air iues for heating air forcombustion purposes by means of the heat transmitted through the wallsof the chamber.

2. A tunnel kiln comprising a masonry structure and a lining at top andsides forming a. tunnel chamber with an intervening sparc, and suchspace subdivided on opposite sides to form a succession of lateralcombustion chambers flanking the tunnel chamber, with independent fueland air inlets to such opposite chambers, and means for independentlycontrolling the combustion in the individual chambers. i

3. A tunnel kiln comprising a masonry st-ructure and a linin forming atunnel chamber enclosed there y with an intervening space, andtransverse partitions dividing the intervening space into combustionchambers, with independently controllable fuel and air inlets to suchcombustion chambers.

4. A tunnel kiln comprising a masonry structure and a lining;v forming atunnel chamber enclosed thereby with an intervening space, andtransverse-.partitions dividing the intervening space into combustion jchambers, with independently controllable fuel and air inlets thereto,and openings in the successive. gpartitions abo-ve the tunnel chamberfor the cumulative outiow of lire gases.

5. A tunnel kiln comprising a tunnel chamber, a. masonry structure enclosin it, successive transverse combustion cham ers formed in theintervening sp-ace, longiltudinal air and gas 'lues and inlets branchingtherefrom, and entering the respective combustion chambers, land damperscony 'trolling such inlets.

6. A tunnel kiln comprising a masonry structure, and a tunnel liningenclosed thereby with 'transverse partitions sub-dividing theintervening and man-holes through the roof ofthe" structure for givingaccess to the spaces between such partit'ions.

7. A tunnel kiln comprising a masonry structure, and a tunnel liningenclosed thereby' with transverse partitions subdividing the interveningspace, manholes through the roof of the structure for giving access tovthe spaces between suchvpartitions, said manholes having a closurecomprising a lowerperforated tile for the admission of a pyrometer andan upper tile for closing this opening.

8. A tunnel kiln comprising a masonry arch having inbuilt inwardlyprojecting refractory partitions, such partit-ions having flanges attheir inner projecting ends, and tiles resting on such anges and shorterthan the spaces between the partitions, and free to be. removed andreplaced without disturbing the partitions.

9. A tunnel kiln comprising a masonry arch built with inwardlyprojecting refractory partitions having projections interlocked with themasonry of such arch, and having flanges at their inner projecting ends,and lining tiles for such tunnel chamber shorter than the space betweensuch partitions and supported between such partit-ions by resting on theinner lateral projections thereof.

l0. In a tunnel kiln, a masonry structure and refractory transversepartition tiles built into such structure, having on their outerportions lateral projections interlocking with the masonry, such tilesprojecting inwardlytherefrom to a tunnel chamber and having lateralprojections on their inner edge portions, and lining tiles for suchtunnel chamber shorter than the spaces between such partitions andsup-ported between such partitions by resting on the inner lateralprojections thereof.

11. A tunnel kiln comp-rising a tunnel lining and an enclosing masonrystructure with refractory transverse partitions built into andinterlocked with such structure and projecting inwardlyjto such lining,the lining comprisingupright side tiles resting on the sole member ofthe masonry, and supported againstoutward displacement by contact withthe upright portions of such partitions, and top tiles supported by saidpartitions and entering between the top of said side tiles whereby tohold them against inward displacement.

-12.`A tunnel kiln comp-rising an arched masonry structure, comprisingan outer wall having poke holes, a tunnel lining, transverse combustionchambers, longitudinal feed lues and communicating branch flues,

said branch flues having controlling means comprising slidable dampers,said dampers comprising horizontal sliding bricks adapted to be operatedindependently by pokers introduced through said hol.

13. A tunnel kiln 'comprising an. arched masonry structure, a tunnellining, transverse combustion chambers and longitudinal feed fluesrespectively for the induction of yair and gas', and means forcontrolling the inlet of air to said air flue, comprising a verticalinlet opening to such iue and a tile damper slidable horizontally oversaid opening,

isa

14. A tunnel kiln comprising a masonry arch with transverse partitiontiles built into such structure and projecting inwardly, said tilesbeing built together in arch form and having continuous outer flangesinterlocked with such masonry arch.

15. A tunnel kiln comprising a tunnel lining and an enclosing masonrystructure, with partition tiles interlockedl witlrsuch masonry andprojecting inwardly therefrom to engage said lining, and the lininghaving side and top tiles jointed together and the top tiles supportedby the partition tiles.

16. A tunnel kiln comprising an arched masonry' structure withsuccessive transverse partitions built thereinto and projecting inwardlytherefrom, a tunnel lining engaging such partitions, the interveninglateral spaces constituting combustion chambers and the spaces above thetunnel lining forming eduction chambers, and the partitions formed withcoinciding outflow openings throuv'h which the fire gases pass from saideductlon chambers in longitudinal di' rection.

17. A tunnel kiln comprisingatunnellining and an enclosing masonrystructure, with transverse partitions built into such structure, saidlining comprising side and top tiles, said side tiles having bottomflanges fitting in grooves to prevent their displacement and heldagainst the partitions by the top tiles which fit between them andprevent their upper ends falling inward.

18. A tunnel kiln comprising an arched masonry st-ructure, a tunnellining, transverse combustion chambers andl longitudinal gas and airfeed flues, said feed flues corn-A municatingb with said chambers by aseries of branch flues, and dam ers independently controlling saidbranch u'es.

19. A tunnel kiln comprising an arched masonry structure, a tunnellining, transverse combustion chambers, longitudinal feed fluesandcommunicating branch flues, said branch flues having controlling means,comprising slidable dampers operating to regulate the combustion in saidchambers.

20. A tunnel kiln having a continuous tunnel lining, and an enclosingmasonry structure with combustion chambers formed inthe interveninspace, air heating flues extending from t e discharge end of the kilnthrough such masonry longitudinally along the tunnel lining, and meansfor causing air to How therethrou h in direction opposite to` the travelof t e wares through the tunnel, whereby the air is heated from suchwares, and controllable means for conducting such heated air to suchcombustion chambers for feeding the combustion.

21. In a tunnel kiln, means located toward the emergin end thereof forutilizing the heat radiated from the treated wares, while cooling,comprising successive pipes crossing the t-unnel chamber transversely,and means for flowing air successively through said pipes, said meanscomprising a fan and controlling means comprising a. slidable damperoperating to regulate the flow of air into said pipes.

22. A continuous tunnel'kiln comprising a tunnel lining and, anenclosing masonry structure with combustion chambers formed in theintervening space, and transverse partitions dividing the interveningspace, to form a zigzag flue, said partitions each extending across thetop and partly down one side of said lining and down the opposite sideto the bottom, and said partit-ions being alternated to connect the flueon alternately opposite sides, whereby the gases. in such flue circulateover the top and sides of the tunnel lining.

. 23. In a tunnel kiln comprising a tunnel lining and an enclosingmasonry structure wit-l1 intervening transverse partitions, combustionchambers formed in such structure and zigzag flues conducting the wastegases from such chambers formed between such partitions, whereby the`fire gases circulating through such flues communicate heat through thetunnel lining to heat the wares advancing through the tunnel toward thefiring zone. a

24. In atunnel kiln comprising a masonry structure and a tunnel liningenclosed thereby with intervening partitions forming combustion chambersand. flues, and an outlet for fire gases from such filles to anexhaust,means for drawing off from the tunnel chamber gases generated thereinconsisting of a damper-controlled opening communicating between suchtunnel chamber and exhaust. v 25. In a. tunnel kiln, means locatedtoward the emerging end thereof for cooling the treated wares,comprising successive pipes crossing the tunnel chamber transversely,and means for flowing air successively through said pipes.

26. In atunnel kiln, means located toward the emerging end thereof forcooling the treated wares, comprising successive pipes crossing thetunnel chamber transversely, means for flowing air successively throughsaid pipes, such pipes being grouped 1n series and connected to headerflues at opposite ends, and means for flowing air through such flues andsuccessive groups of pipes.

27. In a tunnel kiln, means located toward the emerging end thereof forcooling the treated wares, comprising successive pipes crossing thetunnel chamber transversel and means for flowing air successive ythrough said pipes, said pipes having inward heat conducting projectionsintercepting the flow of air.

28. A continuous Inutile furnace compris ing a tunnel lining for the topand s1des of the tunnel chamber, combustion chambers for directlyheating such lining, and flues formed against said lining on the top andsides at a different longitudinal position of the furnace for leading inand preheating air to support combustion.

29. A continuous muflie furnace comprising an enclosing masonrystructure, a tunnel lining within it, and a plurality'of independentlycontrollable lateral combustion chambers formed in the intervening spaceover a firing zone in said furnace for directly heating such lining, acommon longitudinal exhaust passage through said space connecting witheach of said combustion chambers to receive and unite the fire gasestherefrom, and a single circuitous flue formed directly against saidlinin between said zone and the entering end o the furnace receiving theunited gases from said passage and leading such gases in a circuitouspath over a :one of the furnace between its entering end and thecombustion chambers to preheat the Wares traveling through the tunnel.

In Witness whereof, `I have hereunto signed my name.

LOUIS A. WITTE.

